Steam generator



H. J. KERR STEAM GENERATOR Sept. 5, 1933.

Filed Feb. 27, 1929 2 Sheets-Sheet, 2

jmvz TOR ATTOENEYS at a higher steam Patented Sept. 5, 1933 UNITED STATES PATENT OFFICE The Babcock K Wilcox Company,

Bayonne,

N. J., a corporation of New Jersey Application February 27, 1929. Serial No. 343,072

16 Claims.

This invention relates to a steam generating system in which a boiler is provided for generating steam at the desired pressure and a supplemental or stand-by boiler is provided in which water under much higher pressure is kept heated generating temperature so that upon a sudden increased demand for steam in the main boiler a connection can be opened between the two boilers, thus introducing a supply of steam at the lower pressure to the main boiler from the high pressure or stand-by boiler.

In some installations it is desired to have a steam turbine operating at normal speed on the line at no load driving an electric generator upon which full load may be thrown instantly. The rotor of the turbo-generator in such installations has sufiicient kinetic energy to keep the speed above the allowable minimum for a few seconds after full load comes on. Due to the fact that it is not possible to make the boiler pick up full load within a few seconds, the stand-by boiler containing water at the boiling temperature under the higher pressure is available for supplying steam until the main boiler can be brought up to full load. The release of pressure causes the water in the stand-by boiler to flash into steam.

The invention will be understood from the description in connection with the accompanying drawings, in which Fig. 1 is a somewhat diagrammatic side view showing an illustrative embodiment of the invention; Fig. 2 is a vertical section on an enlarged scale through one of the valves; Fig. 3 is a similar view through another one of the valves and Fig. 4 is a view partly broken away similar to Fig. 1 showing the standby.boiler operating as an economizer for the main boiler.

In the drawings, reference character 1 indicates the furnace of a water tube boiler that is provided with a plurality of oil burners 2 that receive combustion air from the air pump 3.

A steam boiler of the water tube type is indicated above the furnace 1 and is provided with the usual steam and water drum 4. A valved pipe 5 leads from the outlet of the superheater 6 of the boiler to the steam turbine 7 of a turbogenerator.

The waste gases from the furnace 1 after passing over the boiler heating surfaces of the boiler above the furnace pass downwardly through a flue 10 to a stack. A stand-by or high pressure boiler is located in the flue 10. An oil burner 11 may be located in the upper portion of the flue 10 to supplement the amount of heat that the stand-by boiler receives. The tubes 12 of the stand-by boiler are made to withstand high pressures and are installed in a manner similar to economizer tubes so that the stand-by boiler tubes can be used as economizer tubes during the 60 normal operation of the low pressure or main boiler. The upper ends of the tubes 12 are connected to a steam and water drum 13 from the lower side of which a pipe 14 extends to a bubble separator 15 that is provided with baffles 16 thereacross. A steam pipe 17 leads from the upper portion of the bubble separator 15 to the upper part of the steam and water drum 13. A pipe 18 leads from the lower portion of the bubble separator 15 to a high pressure circulating pump .v

19 from the outlet of which a valved pipe 20 leads to the header 22' connected to the lower ends of the tubes 12.

A high pressure feed pump 23 takes water from the feed water pipe 30 and forces it through the valved pipe 24 into the circulation system of the high pressure boiler, the connection being shown to the pipe 18.

A safety valve 25 is provided on the drum 13 and any steam that escapes therefrom is led by means of the pipe 26 to the steam space of the steam and water drum 4. A pipe 27 leads from the upper side of the drum 13 to the drum 4. This pipe is provided with a reducing valve 28 and also with a stop valve 29 between the valve 28 and the drum 13. The stop valve 29 is shown on an enlarged scale in Fig. 2 and is so constructed that fluid under pressure entering the top thereof will compress the spring in the upper portion and open the valve to permit fluid to pass through the pipe 27 in whichthis valve is located.

A branch pipe 32 leads from the feed water pipe 30 to the main feed pump 33 from the outlet of which the pipe 21 having a valve 21 therein leads to the steam and water drum 4. A valved connection 36 leads from the pipe 21 to the pipe 20.

A steam pipe 3'7 leads from the steam space of the steam and water drum 4 and has a valved branch 38 leading to the burner 11, a valved branch 39 leading to the steam cylinder of pump 33, a valved branch 40 leading to the high pressure circulating pump 19 and a valved branch 41 leading to the steam cylinder of the high pressure feed pump 23.

A valved branch 42 leads from the superheated steam pipe 5 to the air pump 3 and a branch pipe 43 leads from the pipe 5 and has branches leading to the burners 2. Exhaust pipes 44, 45, 46 and 47 lead from the pumps 23, 19, 33 and 3 respec- 110 tively, to a pipe 48 which leads to an oil heater 49. A pipe 50 for the condensed steam leads away from the oil heater 49.

An oil pipe 51 leads from a source of oil supply and a branch 52 leads from the pipe 51 to the oil pump 53 from which a valved pipe 54 leads to the oil heater 49. An outlet pipe 55 extends from the oil heater 49 and has branches 55 to the burners 2. This pipe also extends to the oil burner 11 through a valved branch 55", and a return pipe 56 extends back to the pipe 52 so that the pump 53 can keep the oil in circulation through the heater 49 and thus keep hot oil at the burners 2 and 11. A valved steam pipe 53 leads from the steam line 5 to the pump 53.

The governor 5'7 of the turbine '7 is connected to a control valve 58 in a compressed air pipe 59 that.

contains air under pressure from a source (not shown) for controlling the operation of certain valves in the steam generating system. Valved branches 59' extend from the pipe 59 to valves of the same type as the valve 29 for controlling some of the burners 2. A valved branch 60 extends from the steam pipe 43 to one or more of the burners 2, to which burner or burners a valved oil pipe branch 61 leads from the oil pipe 55.

Branch pipes extend from the main pipe 59 to control valves 62, 63, 64 and 65 in pipes 40, 41, 42, and 53, respectively, and to the stop valve 29. A section onan enlarged scale through the valve 65, for example, is shown in Fig. 3. The entry of air through the pipe 59 lifts the valve stem against the pressure of the spring at the upper end of the valve casing, thereby opening the valve to permit steam to pass through the pipe 53 into the steam cylinder of the pump.

The operation is as follows:

Assume-that the turbo-generator '7 is running idle at normal speed and that a heavy load is suddenly thrown upon it.= While the turbo-generator 7 is running idle the main boiler is generating merely enough steam to keep the turbine running. This can be done, for example, by operating the middle one of the burners 2, the hand valve in the steam branch 66 and the hand valve in the oil branch 61 being so adjusted that the proper amount of oil will be sprayed into the furnace for this purpose. The hot products f combustion from the main boiler pass across the tubes 12 of the stand-by boiler as they pass downwardly through the flue 10. The hand valve in the branch oil pipe 55" leading to the burner 11 and the hand valve in the branch steam pipe 38 are adjusted to increase the amount of heat for the stand-by boiler if needed. The oil pump 53 keeps the oil in circulation so that hot oil is available at any instant for the burners. Communication between the stand-by boiler and the main boiler is shut oil by means of stop valve 29 and the water is kept slowly circulating in the standby boiler by means of the circulating pump 19. The high pressure pump 23 supplies water to make up for evaporation losses or leakage in the stand-by boiler. The bubble separator 15 separates steam from water therein and permits the steam to return through the pipes 1'1 so that the water will be circulated by means of the pump 19. The pipes 21 and 35 are available for permitting the feed water to pass through them into the drum 4 of the main boiler during the idling period, the valve in the cross connection 36 being closed during this time.

When the load comes on the turbo-generator its speed begins to decrease, whereupon the governor 57 opens the valve 58 in the air control line 59. The air entering through one of the branches from the high pressure air pipe 59 opens the stop valve 29 in the pipe 2'7 between the drum 13 and drum 4 and permits water to pass into the main boiler through the pressure reducing valve 28 and flash into steam. The size of the stand-by boiler and the amount of water therein will be determined by the amount of additional steam that is needed until the main boiler can be brought up to full rating. The connection between the drum 4 and the drum 13 is then opened to avoid reduction in pressure, the valve 21' and the valve in the pipe 20 closed, and the valve in the connection 36 opened by hand. The valves in the branch oil pipes 55' leading to the oil burners 2, are opened by the air passing through the branches 59' so that these burners are immediately started at full blast. The air through one of the branches from the pipe 59 also opens the valve in steam pipe 42 to permit the air pump 3 to furnish full pressure of air to the burners 2.

When the pressure in the stand-by boilerdecreases sufliciently to be substantially equal to that of the main boiler, valves are operated so that the main feed pump 33 causes water to pass through the tubes 12. These tubes then operate as an economizer for the boiler with the drum 13 full of water as shown in Fig. 4. The valves 62 and 63 leading to the circulating pump 19 and high pressure feed pump 23 are of the same type as the valves 64 and 65, but are closed instead of opened when air from the pipe 59 enters. When the main boiler 6 operates as a normal boiler having the economizer in the fine 10 through which the feed water from the pump 33 passes, as shown in Fig. 4, the hand valves in pipes leading to the pumps 19 and 23 may be closed.

I claim:

1. In a steam generator, a boiler, a stand-by boiler under higher pressure than said first named boiler, said boiler being connected through a pressure reducing device, and means to cause said stand-by boiler to operate as an economizer for said first named boiler under normal load conditions.

2. In a steam generator, a boiler having an economizer; means to close the connection from said economizer to said boiler and generate high pressure steam in said economizer when said boiler is operating at small load, and means to feed water to said boiler independently of said economizer.

3. In a steam generator, a boiler having an economizer, means to close the connection from 30 said economizer to said boiler and generate high pressure steam in said economizer when said boiler is operating at small load and means to open said connection operated by a sudden increase of load on said boiler.

4. In a steam generator, a boiler having an economizer, a connection with a pressure reducing valve therein between said boiler and said economizer, means to close the connection from said economizer to said boiler and pressure steam in said economizer when said boiler is operating at small load, said economizer being provided with an upper drum to operate as a steam and water separator when said connection is closed.

5. In a steam generator, a boiler having an economizer, a connection with a pressure reducing valve therein between said boiler and said economizer, means to close the connection from generate high pressure steam in said economizer when said boiler is operating at small load, said economizer being provided with an upper drum to operate as a steam and water separator when said connection is closed and a circulating pump to cause water to circulate through said economizer at the same time.

6. In a steam generator, a boiler having an economizer, means to close the connection from said economizer to said boiler and generate high pressure steam in said economizer when said boiler is operating at small load, said economizer being heated by waste gases from said boiler, and a supplementary heat source for the said economizer.

7. In a steam generator, a boiler, a stand-by boiler under higher pressure than said first named 1 boiler, means to cause steam to pass from said speed of said turbine.

8. In a steamgenerator, a boiler, a stand-by boiler under higher pressure than said first named boiler, means to cause steam to pass from said high pressure boiler to the other boiler, a turbine driven by steam from said boiler, and burners for the furnace of said boiler set into operation by an increase of the load on the turbine which causes a decrease in the speed of said turbine;

9. In a steam generator, a boiler, a standby boiler under higher pressure than said first named boiler, means to cause steam to pass from said high pressure boiler to the other boiler, a turbine driven by steam from said boiler, oil burners for the furnace of said boiler set into operation by an increase of the load on the turbine which causes a decrease in the speed of said turbine, and means for heating and circulating the oil for said burners.

10. In a steam generator, a boiler, a stand-by boiler under higher pressure than said first named boiler, means to cause steam to pass from said high pressure boiler to the other boiler when the load on the latter increases, and means to heat said stand-by boiler aside from the products of combustion from said first named boiler.

11. In a steam generator, a boiler, a stand-by boiler under higher pressure than said first named boiler, means to cause steam to pass from said high pressure boiler to the other boiler when the load on the latter increases, and a pressure reducing valve between said boilers.

12. In a steam generator, a boiler having an economizer, means to close the connection from said economizer to said boiler and generate high pressure steam in said economizer when said boiler is operating at small load, a turbine driven by said boiler and means to open said connection when the load on said turbine increases.

13. In a steam generator, a boiler having an economizer means to close the connection from said economizer to said boiler and generate high pressure steam in said economizer when said boiler is operating at small load, a turbine driven by said boiler and means to open said connection and increase the rate of combustion in the furnace of said boiler when the load on said turbine increases.

14. In a steam generator, a furnace, a main boiler heated by said furnace and subject to widely fluctuating load conditions, a stand-by boiler, means for maintaining a substantial amount of water in said stand-by boiler at a high temperature and under a substantially higher pressure than in said main boiler, a fluid connection between said stand-by boiler and the steam space of said main boiler, valve means controlling said fluid, connection and operable to maintain said stand-by boiler operatively independent of said main boiler during low loads on the latter and to permit the passage of hot water at high pressure to the steam space of said main boiler at high load periods, and means for substantially increasing the amount of steam delivered by said main boiler on a sudden increase in load thereon comprising means responsive to an increase in load on said main boiler for operating said valve means to open: said fluid connection between the boilers.

15. In a steam generator, a furnace, a main boiler heated by said furnace and subject to widely fluctuating load conditions, a stand-by boiler, means for maintaining a substantial amount of Water in said stand-by boiler at a high temperature and under a substantially higher pressure than in said main boiler, a fluid connection between said stand-by boiler and the steam space of said main boiler, valve means controlling said fluid connection and operable to maintain said stand-by boiler operatively independent of said main boiler during low loads on the latter and to permit the passage of hot water at high pressures to the steam space of said main boiler at high load periods, a conduit system for supplying feed water to said main boiler either directly or via said stand-by boiler, and means for substantially increasing the amount of steam delivered by said main boiler on an increase in load thereon comprising means for closing the feed water connection directly to said main boiler and opening said feed water connection via said standby boiler.

16. In a steam generator, a furnace, a main boiler heated by said furnace and subject to widely fluctuating load conditions, a stand-by boiler, means for maintaining a substantial amount of water in said stand-by boiler at a high temperature and under a substantially higher pressure than in said main boiler, means for supplying fuel and air for combustion to said furnace, a fluid connection between said stand-by boiler and the steam space of said main boiler, valve means controlling said fluid connection and operable to maintain said stand-by boiler operatively independent of said main boiler during low loads on the latter and to permit the passage of hot water at high pressure to the steam space of said main boiler at high load periods, and means for substantially increasing the amount of steam delivered by said main boiler on a sudden increase in load thereon comprising means responsive to an increase in load on said main boiler for operating said valve means to open said fluid connection between said boilers and for increasing the sup= plies of fuel and air to said furnace.

HQWARD J. KERR. 

